In various pyrometallurgical processes, attention has centered of late upon the use of a cyclone chamber into which the fine-grained solids, high-oxygen gases and, if desired, an energy carrier such as a fuel are introduced to undergo reaction.
Cyclones of this type have found application in combustion installations, e.g., furnaces, as well as in pyrometallurgy. Various systems using such cyclones are described in the following publications: "Lexikon der Technik," vol. 7, "Lexikon der Energietechnik und Kraftmaschinen," L-Z, Deutsche Verlagsanstalt Stuttgart, 1965; I.A. Onajew "Zyklonschmelzen von Kupfer und polymetallischen Konzentraten," Neue Hutte 10, 1965, pages 210 et seq.; Printed German Applications (Auslegeschrift) Nos. 11 61 033, 19 07 204, and 20 10 872; Open German Specification (Offenlegungsschrift) No. 21 09 350; Sch. Tschokin, Freiburger Forschungshefte B150, Leipzig, 1969, pages 41 et seq.; G. Melcher et al. and E. Muller in Erzmetall, vol. 28, 1975, pages 313 et seq., vol. 29, 1976, pages 322 et seq., vol. 30, 1977, pages 54 et seq.
The reason why cyclone chambers have been found to be especially effective in pyrometallurgical treatments, and, more generally, for carrying out reactions in which an oxygen-containing gas participates, is that the throughput of the cyclone per unit of reactor volume is high compared to other solid/gas treatment systems. High reaction temperatures can be obtained, thereby permitting volatilization of various components of the solid feed.
There is described in printed German Application (Auslegeschrift) No. 22 53 074, see U.S. Pat. No. 3,915,692, a technique which utilizes a cyclone chamber and which ensures that the reactants are intensely mixed and are caused to react to a considerable extent in a vertical combustion path before entering the cyclone chamber. This system provides a vertical combustion path at the inlet to the cyclone chamber.
The advantage of this system over the operation of a cyclone chamber without a combustion path ahead of the chamber is that is precludes a separation of particles of the feed solid in the cyclone chamber and the entrapment of the separated solids in the molten film which lines the wall of the cyclone chamber and which might prevent these particles from participating in the reaction.
In spite of the advantages of the cyclone chamber, particularly when the latter is operated as described in German Auslegeschrift (printed application) No. 22 53 074, difficulties have been encountered in some cases with the separation of the molten droplets which are entrained by the gases leaving the cyclone chamber. Particularly in pyrometallurgical processes, the collecting surfaces, which are water-cooled grates in most cases, tend to be clogged quickly because the gas entering the cyclone chamber and the gas leaving the cyclone chamber have high loading rates.